Transformer



Jan. 7, 1930. L. H. BURNHAM TRANSFORMER Filed May 20, 1929 Inventor-YLoc ke HBuPn ham, by I 00% His AttOTney.

Patented Jan. 7, 1930 UNITED STATES PATENT OFFICE LOCKE H. BURNHAM, OFPITTSFIELD, MASSACHUSETTS, ASSIGNOR TO GENERAL ELEC- TRIO COMPANY, ACORPORATION OF NEW YORK TRANSFORMER Application filed May 20,

My invention relates to transformers. A shell type transformer has amagnetic core with three legs, the center leg being surrounded by thewindings. In many transformers of this type, the windings are formed offiat coils which are supported in spaced relation so that a coolingmedium such as air or oil may flow through the spaces between the coilsand past the winding leg from one side of the transformer to the other.The winding leg of the core forms an obstruction to the flow of thecooling medium and shields a region behind it where it has been foundthat portions of the winding coils and adjacent por tions of the windingleg itself sometimes be come overheated. The general object of thepresent invention is to provide an improved arrangement and constructionof coil spacers which will convey or direct some of the cooling mediuminto the region behind the winding leg of the core and so avoidoverheating of the coils and winding leg in and adjacent to this region.

The invention will be better understood from the following descriptiontaken in con nection with the accompanying drawing in which Fig. 1 is asectional view of a shell type air blast transformer with winding coilspacers constructed and arranged in accordance with the invention, theview being taken on the line 1'1 of Fig. 2; Fig. 2 is a sectional viewon the line 2-2 of Fig. 1; and Fig. 3 is a view, reduced in size, of oneof the winding coil spacers with one of its sides or faces removed toshow the interior arrangement.

Like reference characters indicate similar parts in the differentfigures of the drawing.

The invention will be explained in connection with the transformer shownin the drawing, this particular transformer being of the usual air blasttype and having a horizontal magnetic core with a central winding legand two outer legs 11 and 12. The winding leg 10 is surrounded by twogroups of spaced low voltage winding coils 13 and an interposed group ofspaced high voltage winding coils 14. The core with the winding coils ismounted horizontally on a hollow base 15 and a hollow cap 16 is mountedon the core 1929. Serial No. 364,484.

and encloses the upper portions of the coils 18 and 14 which projectabove the core. Air may be forced into the base 15 in any manner desiredas by a suitable fan or blower. This air flows upwardly through thespaces between the coils 13 and 14 absorbing heat from these coils andfrom the winding leg 10 of the core, the heated air finally passing outand escaping through openings in the top of the cap 16.

Spacers 17 constructed and arranged in accordance with the inventionsurround the winding leg 10 in the spaces between certain of the coils13 and 14. As shown in Fig. 2, the spacers 1'? are provided only in thespaces between the high and low voltage groups of coils and at the outerend of each of the low voltage groups. Additional spacers of anysuitable construction desired may be provided between the coils of eachgroup and, for the sake of clearness in the drawing, are not shown.

Each spacer 17 has two sides or faces 18 and 19 formed of sheetinsulating material such as pressboard, each having an opening for thewindin leg 10 of the core. The sides 18 and 19 are spaced apart byspacing strips 20 of insulatin material inter aosed between them attheir inner and outer edges and at such other points as may be necessaryto main tam the proper spacing against the pressure of the adjacentwinding coils. These spacing strips 20seal the space between the sides18 and 19 except at the lower outer edge at one side of the core and atthe upper inner edge just above or behind the winding leg 10 at theother side of the core. The sides 18 and 19 of the spacers 17 are cutaway to provide small openings 21 between the interiors of the spacersl7 and the adjacent winding coils just above the winding leg 10. Thehollow spacers 17 thus provide passages or ducts which will directcooling currents of air from the base 15 at one side of thetransformercore to the upper surface of th winding leg 10 and to the adjacent partsof the winding coils 13 and 14 at the other side of the transformercore. The inner edges of the winding coils 13 and M may be spacedslightly from the winding leg 10 as shown in Fig. 2 so that air from theopenings 21 in the spacers 17 may reach all the coils. It will beunderstood, of course that only part of the air supplied to the base 15will flow through the hollow spacers 17 and that a considerable part ofit will flow up past'the winding leg 10 and through all the spacesbetween the coils 13 and 14.

The capacity of atransformer is limited generally, not by its averagemaximum tem perature, but by the highest temperature in any part of it.The invention provides an arrangement which effectively preventsexcessive temperatures in parts of the transformer which would otherwisebe shielded from the cooling medium by the winding leg of the core andwhich would therefore be more highly heated than other parts of thetransformer, thus securing a more uniform heating of the entiretransformer.

The invention has been explained by describing and illustrating aparticular embodiment thereof but it will be apparent that variouschanges'maybe made without departing from the spirit and scope of theinvention as covered by the appended claims.

lVhat I claim as new and desire to secure by Letters Patent of theUnited States is:

1. A shell type transformer having a three legged magnetic core, discwinding coils surrounding the central core leg, and a hollow insulatingspacer between two of said coils,

said spacer having an opening at one side of the core to recelve acoohng medium and a second opening adjacent the inner edge of one ofsaid coils at the other side of the core.

2. A shell type transformer having a three legged magnetic core spaceddisc winding coils surrounding the central core leg, and hollowinsulating spacers surrounding said winding leg in the spaces betweensaid coils, said spacers having openings at one side of the core toreceive a cooling medium and openings adjacent the inner edges of saidcoils at the other side of the core. 7

In'witness whereof, I have hereunto set my hand this 17th day of May,1929.

LOCKE H. BURNHAM.

